Two main rounds of thunderstorms will likely impact southern/eastern Ontario Tuesday and again on Wednesday as a series of disturbances ride along a boundary dividing the hot and humid air to the south from the cooler, less humid air to the north.
Exact timing and intensity of these thunderstorms is difficult to pinpoint, but there is the chance that parts of these regions, especially southwestern Ontario, could be in store for some severe thunderstorms during the period.
The first map below shows the area with the best chance of thunderstorms for Tuesday/Tuesday night...
By Wednesday, high pressure over the southern U.S. will allow the heat and humidity to build over the Ohio Valley and Middle Atlantic region, which will further fuel the storms forming along the northern rim of the high pressure ridge to the north.
A backdoor front will bring drier and cooler air in from the northeast Thursday and Friday, especially to areas north and east of the GTA.
Heavy rainfall and flooding potential for southern Alberta through Tuesday night.....
A slow-moving, upper level storm system will be the primary cause for locally heavy rainfall over extreme southern Alberta through Tuesday night and perhaps into southwestern Saskatchewan.
Rain and embedded thunderstorms could cause some flooding in southern Alberta during the period, especially south of Calgary. Rainfall totals will likely average in the 20-50 mm range with some isolated higher amounts possible.
Wednesday will remain unsettled in southern Alberta, but the heaviest rainfall and thunderstorms will likely shift into Saskatchewan.
I will be out of the office the rest of this week, but will be back for next week.
Widespread above-normal temperatures will likely dominate into the first half of December.
My thoughts on the snow through Tuesday in the East and West.
Other than a blast into western Canada next week, most of the Arctic air will remain north of the Arctic Circle into December with just brief intrusions while mild, Pacific air takes hold from west to east.
Still happy with my old snow map.
Accumulating snow this weekend for parts of southern, central and eastern Ontario.
Wild storm in the West through Tuesday. A little snow in the east for the weekend?